Helicopter blades are mounted by a yoke or head coupling the blades to the mast or drive shaft connected to the helicopter fuselage. The blades and the central head are free to teeter or tile by a small angle relative to the mast. Under normal conditions when the blades are exerting lift on the helicopter fuselage, the helicopter is in a relatively stable condition, and the helicopter mast does not normally teeter excessively relative to the helicopter blades. Incidentally, stops are provided within the yoke or head, to limit the tilting or teetering of the blades relative to the mast. Incidentally, when a helicopter is hovering at a fixed location the "g" force or the acceleration in the helicopter is equal to that of gravity and is equal to 1-g. Under low-g conditions such as a powered descent, the helicopter is less stable because the blades are unloaded of lift, and the blades may tilt excessively relative to the helicopter mast. Further, under severe low-g conditions, and if these conditions are combined with excessive pilot control maneuvers, the rotor head stops are forced into contact with the mast with excessive force to create a bending moment on the mast. Under extreme conditions, the mast may shear, with disastrous results.